The present invention relates in general to drafting and more particularly concerns novel apparatus and techniques for holding rough input material to be reproduced by a draftsman in a formal drawing in a manner that facilitates copying by the draftsman while reducing fatigue, facilitating drafting anywhere on the formal sheet and minimizing undesired blemishes.
The typical prior art approach to preparing formal drawings involves taping both the formal sheet and the informal sheet, usually containing a rough sketch of the material to be copied, to the drafting board. Usually the informal input sheet is considerably smaller than the formal sheet and frequently contains material on both sides. Not infrequently the draftsman must work on the formal sheet on a location spaced so far from the informal input sheet that he must move back and forth between the two locations, increasing the time for completing the work and fatigue. Alternatively, the draftman may tape the input sheet to the formal sheet near the location where he is then working, moving the informal input sheet from time to time. Not only is this time consuming, but removing the tape introduces undesired wrinkles or warps in the formal sheet and the sticky residue of tape may attract contaminants leaving undesired blemishes on the formal sheet. And obtaining access to both sides of the informal input sheet requires at least one untaping and retaping.
There is still another disadvantage of the prior art approach. The draftsman uses mutually perpendicular rules adjustable in angle and position along the entire drafting table. An informal input sheet taped to the formal sheet may interfere with movement of the rules. In moving these rules the draftsman may inadvertently poke the rule between the informal sheet and the formal sheet, thereby dislodging the informal sheet and perhaps introducing a gouge in the formal sheet below. Furthermore, adhesive material from the tape may stick to the rule interfering with its free movement along the formal drafting sheet.
It is an important object of the invention to provide improved methods and means for supporting informal input drafting material.
It is a further object of the invention to achieve the preceding object while overcoming one or more of the disadvantages enumerated above.
It is a further object of the invention to achieve one or more of the preceding objects with apparatus that is relatively inexpensive and easy to fabricate.
It is a further object of the invention to achieve one or more of the preceding objects with apparatus that is convenient to use by draftsmen.
It is still another object of the invention to achieve one or more of the preceding objects with apparatus capable of being used on virtually any drafting board and adaptable for use with a wide variety of formal drawing sizes.